Serevent Diskus inhalation
powder and Serevent inhalation
aerosol contain salmeterol
xinafoate as the racemic form
of the 1-hydroxy-2-naphthoic acid salt of salmeterol. The active component
of the formulation is salmeterol base, a highly selective beta2-adrenergic
bronchodilator. The chemical name of salmeterol xinafoate is 4-hydroxy-a1-[[[6-(4-phenylbutoxy)hexyl]amino]methyl]-1,3-benzenedimethanol,
1 -hydroxy-2-naphthalenecarboxylate.

The molecular weight of salmeterol
xinafoate is 603.8, and the empirical formula is C25H37NO4C11H8O3.
Salmeterol xinafoate is a white
to off-white powder. It is freely soluble in methanol; slightly soluble
in ethanol, chloroform, and isopropanol; and sparingly soluble
in water.

Serevent Diskus Inhalation Powder

Serevent Diskus is a specially designed plastic
device containing a double-foil
blister strip
of a powder formulation of
salmeterol xinafoate intended for oral
inhalation only. Each blister
on the double-foil strip within the device
contains 50 mcg of salmeterol
administered as the salmeterol xinafoate salt
in 12.5 mg of formulation containing lactose. When a blister containing
medication is opened by
activating the device, the medication is dispersed into the air
stream created when the patient
inhales through the mouthpiece.

Serevent inhalation aerosol
is a pressurized, metered-dose aerosol
unit for oral inhalation. It
contains a microcrystalline
suspension of salmeterol
xinafoate in a mixture of
two chlorofluorocarbon propellants (trichlorofluoromethane and dichlorodifluoromethane)
with lecithin. 36.25 mcg of salmeterol
xinafoate is equivalent
to 25 mcg of salmeterol base.
Each actuation delivers 25 mcg of salmeterol base
(as salmeterol xinafoate) from the valve
and 21 mcg of salmeterol base
(as salmeterol xinafoate) from the actuator. Each 6.5-g canister provides
60 inhalations and each 13-g canister provides 120 inhalations.